Hardboard-like panel having a core of wood fibres intimately mixed with asphalt forming 10-30% by weight of the core. The core is porous and contains 50% by volume of air cells. A resin-impregnated paper is glued to the core. The panel is preferably coated with a long life thermosetting acrylic finish, and used as an exterior siding. A process for making same is also described.